I'm in the process of rebuilding my rear duovalve assembly in my 95 S600. The left rear duovalve (A31/1y1) coil winding was open. I took the assembly apart, and measured the diameter of the coil wire at 0.0144 inches. The closest I can translate this to in AWG size is 28 gage HML magnet wire. Total turns was 1, 150. Total DCR of the original coil is 15.4 ohms. After removing the old wire and winding new wire on the bobbin, I get a DCR of 17.7 ohms. This is a 12.99% difference from the original winding. I am assuming that this difference is because the wire size is not 28 gage, but a metric size close to 28 gage. This concerns me. A difference of 10% wouldn't bother me so much. Since this system is logic controlled, I assume that the position of the duovalve plunger can be infinitely adjusted within it's limits. If the coil DCR is off by 13%, I am concerned that the plunger may not be positioned correctly during operation. Does anyone out there have a good understanding of the duovalve operation to tell me if this will cause a noticeable difference in performance?

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1995 S600, 1 of 618 (sold)

"Speed is just a question of money...how fast you wanna go?"

LONG LIVE THE W140!
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Just to be certain, you are discussing the electrically controlled valve which admits/blocks hot water to the heater core?

If so, I think you will be fine. The valve is binary - either fully open, or fully closed. The controls modulate the amount of time it is open to regulate heater core temperature.

So long as it generates a strong enough magnetic field to close the valve (default is fully open, as I'm sure you well know...) you should be fine. The slightly higher impedance will just reduce current draw a bit - which should be fine for the controlling electronics. Lower impedance and the resulting higher current draw would have been a problem.

1,150 windings, huh? You must have more spare time than I do!

- JimY

Super! Thanks a bunch Jim. I don't really have spare time, I just love doing this kind of thing. I enjoy reverse engineering, as well as saving hundreds of dollars!

__________________
1995 S600, 1 of 618 (sold)

"Speed is just a question of money...how fast you wanna go?"

LONG LIVE THE W140!
Visit my Web Page at www.v12uberalles.com